How long does giardia take to present symptoms?

Variable: But usually 7-10 days.

Giardia Infection.: Incubation period is 1 to 14 days (ave of 7 days). Giardiasis is a waterborne illness caused by Giardia parasite. Sx's – there may be no sx's or diarrhea, oily floating stool, gas, nausea, vomiting & abdominal cramps. If untreated it can cause bloody diarrhea, dehydration & weight loss. Diagnosis- via blood test for antibodies & checking stool for parasites.